• angiotensin I-converting enzyme inhibitory peptides;
  • antihypertensive effect;
  • chum salmon;
  • thermolysin


In order to utilize upstream chum salmon as a component of nutraceutical food, their defatted muscle proteins were hydrolyzed with 5% thermolysin. The resulting hydrolysate showed high inhibitory activity against angiotensin I-converting enzyme (inhibitory concentration50= 27.9 protein μg/mL) in vitro. A significant reduction of systolic blood pressure was observed when 500 and 2000 mg/kg of body weight were orally administered into spontaneously hypertensive rats. Angiotensin I-converting enzyme inhibitory peptides contained in the hydrolysate were isolated with various chromatographs. These 6 active peptides were Trp residue-containing dipeptides: Trp-Ala, Val-Trp, Trp-Met, Met-Trp, Ile-Trp, and Leu-Trp. The inhibitory concentration50 values of these dipeptides ranged from 2.5 μM to 277.3 μM.